Add missing dependency for matroska muxer.

Originally committed as revision 26005 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/Makefile

@@ -114,7 +114,7 @@ OBJS-$(CONFIG_MATROSKA_DEMUXER)          += matroskadec.o matroska.o \
                                             riff.o isom.o rmdec.o rm.o
 OBJS-$(CONFIG_MATROSKA_MUXER)            += matroskaenc.o matroska.o \
                                             riff.o isom.o avc.o \
-                                            flacenc_header.o
+                                            flacenc_header.o avlanguage.o
 OBJS-$(CONFIG_MD5_MUXER)                 += md5enc.o
 OBJS-$(CONFIG_MJPEG_DEMUXER)             += rawdec.o
 OBJS-$(CONFIG_MJPEG_MUXER)               += rawenc.o